1. Field of the Invention
This invention relates to float valve systems and in particular but not solely float valve systems for respiratory humidification systems.
2. Description of the Prior Art
A respiratory humidification system includes a humidifier which is supplied with liquid water flow and a flow of gases (for example air including oxygen or an anaesthetic gas). The aim of the humidifier is to combine some of the water in the form of water vapour with the gas, thus raising the level of humidity of the gases and making it easier for a patient in a hospital or someone else in need of such gases to inhale them.
A humidifier in which the gases absorb water vapour from water or a water laden surface usually comprises a humidification chamber containing water and a heater base used to evaporate the water. A crucial aspect of respiratory humidifiers is in the control of the liquid water flow. It is imperative that liquid water not be allowed to pass directly to the patient for obvious reasons. Therefore, within the humidification chamber water valves are commonly used in various configurations to regulate the water flow.
Some prior an water valve mechanisms have been of a single valve type, configured with actuating means in order to stop the water entering the humidification chamber. An example is described in our U.S. Pat. No. 4,913,140. A solitary valve may give rise to difficulties in regard to reliability, as a problem with, for example, the valve seal or the actuating mechanism may cause overfilling. For this reason, prior respiratory humidification systems have introduced double valve mechanisms in a bid to increase reliability and thus the safety of the humidifier. An example is U.S. Pat. No. 4,529,867 to Veinosky et al. The double water valve mechanism described by Velnosky however, does not attempt to halt the flow of liquid water but merely to direct it elsewhere. A double valve configuration is disclosed in the aforesaid U.S. Pat. No. 4,913,140.
It is, therefore, an object of the present invention to provide a float valve and/or a respiratory humidifier which provides the public with a useful choice.